Phase relations, structure, properties and DFT study of compounds in the Sc-rich part of the systems Sc-{Mn,Fe,Co,Ni}-Ga

0559166 - ÚFM 2023 RIV CH eng J - Článek v odborném periodiku
Romaka, V. V. - Rogl, G. - Binder, G. - Michor, H. - Buršík, Jiří - Grytsiv, A. - Giester, G. - Rogl, P.
Phase relations, structure, properties and DFT study of compounds in the Sc-rich part of the systems Sc-{Mn,Fe,Co,Ni}-Ga.
Journal of Alloys and Compounds. Roč. 919, OCT (2022), č. článku 165540. ISSN 0925-8388. E-ISSN 1873-4669
Institucionální podpora: RVO:68081723
Klíčová slova: Scandium alloys and compounds * Phase diagrams * Crystal structure * Magnetization * Mechanical properties * Electronic band structure
Obor OECD: Condensed matter physics (including formerly solid state physics, supercond.)
Impakt faktor: 6.2, rok: 2022
Způsob publikování: Omezený přístup
https://www.sciencedirect.com/science/article/pii/S0925838822019314?via%3Dihub

Phase relations have been derived for the Sc-rich parts of the ternary systems Sc-T-Ga at 850 & DEG,C (T = Mn,Fe,Co,Ni) as well as for the corresponding regions of the pertinent binary systems. Sc4Mn was not observed, but hexagonal Sc2Ga (space group P6(3)mc , unique type) is a binary phase (at 29-31 at% Ga) with a peritectic decomposition temperature (at 1075 & DEG,C) close to the corresponding eutectic with scandium at 1065 & DEG,C and 17.5 at% Ga. Electron microprobe analyses (EPMA) revealed very limited solid solubilities at 850 & DEG,C of T-elements in Sc (< 2 at% T). Although the maximal solubility of Ga in Sc at 850 & DEG,C is about 1 at% Ga, it renders the Sc-phase brittle. An X-ray single crystal structure analysis and TEM investigation defined Sc2+xNi1-x (x = 0.15) as a highly disordered Ti2Ni-type related to the type of disorder known for Dy5Pd2. Whereas the isothermal ternary sections for Sc-{Mn,Fe}-Ga are characterized by one ternary compound, Sc-54{Mn,Fe,Ga}(17) with the orthorhombic Hf54Os17-type (space group Immm), the systems with Co, Ni contain a so-called kappa (& UKappa,) phase, Sc-10(Co1-xGax)(3)Co and Sc-10(Ni1-xGax)(3)Ni. Both phases are occupation variants of the & UKappa,-Hf9Mo4B-type (space group P6(3)/mmc). Besides that, the Sc-Co-Ga system at 850 & DEG,C comprises also a hitherto unknown representative of the Hf54Os17-type as well as two further ternary solid solution phases: Sc15-x-y?yCo3+x-zGa1+z (unique structure type, space group Immm, x = 1.60, y = 0.58, 0 <= z <= 0.82) and Sc50+xCo13-zGa3+z (epsilon-Mg26-xAg7+x type, space group Fm-3, x = 0.84, 0 <= z <= 1). For all compounds the crystal structures were derived from X-ray single crystal studies, some even at several compositions. The characteristic features of all structure types are non-regular Sc-icosahedra centered by (T,Ga) atoms. Whereas & UKappa,-Sc-10(T1-xGax)(3)T phases (T = Co,Ni) form a typical network of corner-connected empty octahedra Sc-6, which encompass Sc-centered icosahedra Sc6Ga6 and T-centered trigonal prisms T[Sc-6], the Sc-54(T,Ga)(17) phases are made of (T,Ga)-centered defect icosahedron-clusters (T = Mn,Fe,Co). The ternary compounds exhibit remarkable large homogeneity regions mainly at practically constant Sc-contents i.e. deviating only slightly from T/Ga exchange pointing towards Sc-richer limits: at 850 & DEG,C from 12 to 14.6 at% Ga for the Co-& UKappa,-phase and from 2.1 to 15.4 at% Ga for the Ni-& UKappa,-phase, from about 6-12 at% for the phases Sc-54{Mn,Co,Ga}(17) , but from 2.8 to 12.3 at% Ga in the case of Sc-54{Fe,Ga}(17). It should be mentioned that Sc-54{Fe,Ga}(17) as well as & UKappa,-Sc-10(Ni,Ga)(4) approach the corresponding binary system almost joining with binary cubic Sc29Fe6 or at least indicating a vanishing instability for the binary hypothetical kappa phase Sc10Ni4.
Trvalý link: https://hdl.handle.net/11104/0332576